title: Development of reduced kidney function in rheumatoid arthritis.
abstract: BACKGROUND
  Rheumatoid arthritis (RA) is associated with a variety of kidney disorders. However, it is unclear whether the development of reduced kidney function is higher in patients with RA compared to the general population.
  
  
  METHODS
  Retrospective review.
  
  
  METHODS
  Incident adult-onset RA cases (813) and a comparison cohort of non-RA individuals (813) in Olmsted County, MN, in 1980-2007.
  
  
  METHODS
  Baseline demographic and clinical variables.
  
  
  RESULTS
  Reduced kidney function: (1) estimated glomerular filtration rate (eGFR)<60mL/min/1.73m(2) and (2) eGFR<45mL/min/1.73m(2) on 2 consecutive occasions at least 90 days apart; cardiovascular disease (CVD); and death.
  
  
  METHODS
  The cumulative incidence of reduced kidney function was estimated adjusting for the competing risk of death.
  
  
  RESULTS
  Of 813 patients with RA and 813 non-RA individuals, mean age was 56±16 (SD) years, 68% were women, and 9% had reduced kidney function at baseline. The 20-year cumulative incidence of reduced kidney function was higher in patients with RA compared with non-RA participants for eGFR < 60mL/min/1.73m(2) (25% vs 20%; P=0.03), but not eGFR<45mL/min/1.73m(2) (9% vs 10%; P=0.8). The presence of CVD at baseline (HR, 1.77; 95% CI, 1.14-2.73; P=0.01) and elevated erythrocyte sedimentation rate in patients with RA (HR per 10-mm/h increase, 1.08; 95% CI, 1.00-1.16; P=0.04) was associated with increased risk of eGFR<60mL/min/1.73m(2). eGFR<60mL/min/1.73m(2) was not associated with increased risk of CVD development in patients with RA (HR, 0.99; 95% CI, 0.63-1.57; P=0.9), however, a greater reduction in GFR (eGFR<45mL/min/1.73m(2)) was associated with increased risk of CVD (HR, 1.93; CI, 1.04-3.58; P=0.04).
  
  
  CONCLUSIONS
  Reduced kidney function was defined by estimating equations for kidney function. We are limited to deriving associations from our findings.
  
  
  CONCLUSIONS
  Patients with RA were more likely to develop reduced kidney function over time. CVD and associated factors appear to play a role. The presence of RA in individuals with reduced kidney function may lead to an increase in morbidity from CVD development, for which awareness may provide a means for optimizing care.
authors.affiliation: Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN. Electronic address: hickson.latonya@mayo.edu.
authors.forename: LaTonya J
authors.initials: LJ
authors.lastname: Hickson
authors.affiliation: Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo Clinic, Rochester, MN; Division of Rheumatology, Mayo Clinic, Rochester, MN.
authors.forename: Cynthia S
authors.initials: CS
authors.lastname: Crowson
authors.affiliation: Division of Rheumatology, Mayo Clinic College of Medicine, Rochester, MN.
authors.forename: Sherine E
authors.initials: SE
authors.lastname: Gabriel
authors.affiliation: Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN.
authors.forename: James T
authors.initials: JT
authors.lastname: McCarthy
authors.affiliation: Division of Rheumatology, Mayo Clinic College of Medicine, Rochester, MN; Division of Epidemiology, Mayo Clinic College of Medicine, Rochester, MN.
authors.forename: Eric L
authors.initials: EL
authors.lastname: Matteson
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007674:Kidney Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
keywords: Cardiovascular disease; estimated glomerular filtration rate (eGFR); glomerulonephritis; kidney dysfunction; mortality; renal progression; rheumatoid arthritis (RA)